Field of the Invention
The invention relates to the gasification of biomass, and more particularly to an entrained-flow gasifier and a gasification method using the same for synthesizing syngas from biomass fuel in the presence of microwave-excited plasma.
Description of the Related Art
Biomass gasification process generally includes fixed bed gasification, fluidized bed gasification, entrained flow gasification. The fixed bed gasification has defects such as low gasification temperature, high tar content, and low-quality syngas. The fluidized bed gasification has a moderate gasification temperature and convenient feeding and discharging, to ensure the stable fluidization, the furnace temperature must be controlled to be moderate. Low gasification temperature results in high content of tar in the syngas. The tar is difficult to remove and easily blocks and corrodes the valves, pipes, and auxiliary equipment. The removal of the tar costs much. The entrained flow gasification has a high and uniform reaction temperature, high gasification efficiency, and the tar is completely cracked. However, the entrained flow gasification has a high requirement on the particle size of the raw materials. In general, the particle size should be less than 0.1 mm. Biomass contains much cellulose, which is very difficult to be crushed to have a small particle size to meet the requirement of the entrained flow bed. The smaller the required particle size is, the larger the abrasion of the crusher is, and the higher the energy consumption is. Large particle size causes the low carbon conversion rate and low cold gas efficiency, which greatly limits the application of conventional entrained flow beds in the synthesis of syngas.